The use of historical collections to estimate population trends: a case study using Swedish longhorn beetles (Coleoptera: Cerambycidae)

Long term data to estimate population trends among species are generally lacking. However, Natural History Collections (NHCs) can provide such information, but may suffer from biases due to varying sampling effort. To analyze population trends and range-abundance dynamics of Swedish longhorn beetles (Coleoptera: Cerambycidae), we used collections of 108 species stretching over 100 years. We controlled for varying sampling effort by using the total number of database records as a reference for non-red-listed species. Because the general frequency of red-listed species increased over time, a separate estimate of sampling effort was used for that group. We observed large interspecific variation in population changes, from declines of 60\% to several hundred percent increases. Most species showed stable or increasing ranges, whereas few seemed to decline in range. Among increasing species, rare species seemed to expand their range more than common species did, but this pattern was not observed in declining species. Historically, rare species did not seem to be at larger risk of local extinction, and population declines were mostly due to lower population density and not loss of sub-populations. We also evaluated the species' declines under IUCN red-list criterion A, and four currently not red-listed species meet the suggested threshold for Near Threatened (NT). The results also suggested that species' declines may be overlooked if estimated only from changes in species range

Testing the effectiveness of the Forest Integrity Assessment: a field-based tool for estimating the condition of tropical forest

1. Global targets to halt biodiversity losses and mitigate climate change will require protecting rainforest beyond current protected area networks, necessitating responsible forest stewardship from a diverse range of companies, communities and private individuals. Robust assessments of forest condition are critical for successful forest management, but many existing techniques are highly technical, time-consuming, expensive, or require specialist knowledge. 2. To make assessment of tropical forests accessible to a wide range of actors, many of whom may be limited by resources or expertise, the High Conservation Value Resource Network (HCVRN), with the SE Asia Rainforest Research Partnership (SEARRP), developed a South East Asian version of the Forest Integrity Assessment (FIA) tool as a rapid (< 1 hour) method of assessing forest condition in the field, where non-experts respond to 50 questions about characteristics of the local environment while walking a site transect. Here, we examined the effectiveness of this survey tool by conducting ~ 1,000 assessments of forest condition at 16 tropical rainforest sites with varying levels of disturbance in Sabah, Malaysian Borneo. 3. We found good agreement (R-squared range: 0.50 – 0.78) between FIA survey scores and independent measures of forest condition, including biodiversity, vegetation structure, aboveground carbon, and other key metrics of ecosystem function, indicating that the tool performed well. Although there was variation among assessor responses when surveying the same forest sites, assessors were consistent in their ranking of those sites, and prior forest knowledge had a minimal effect on the FIA scores. Revisions or further training for questions where assessors disagree, for example on the presence of fauna at a site, could improve consistency. 4. We conclude that the FIA survey tool is a robust method of assessing forest condition, providing a rapid and accessible means of forest conservation assessment. The FIA tool could be incorporated into management practices in a wide range of forest conservation schemes, from sustainability standards, to community forestry and restoration initiatives. The tool will enable more organisations and individuals to understand the conservation value of the forests they manage, and to identify areas for targeted improvements

Comparing Aerodynamic Efficiency in Birds and Bats Suggests Better Flight Performance in Birds

Flight is one of the energetically most costly activities in the animal kingdom, suggesting that natural selection should work to optimize flight performance. The similar size and flight speed of birds and bats may therefore suggest convergent aerodynamic performance; alternatively, flight performance could be restricted by phylogenetic constraints. We test which of these scenarios fit to two measures of aerodynamic flight efficiency in two passerine bird species and two New World leaf-nosed bat species. Using time-resolved particle image velocimetry measurements of the wake of the animals flying in a wind tunnel, we derived the span efficiency, a metric for the efficiency of generating lift, and the lift-to-drag ratio, a metric for mechanical energetic flight efficiency. We show that the birds significantly outperform the bats in both metrics, which we ascribe to variation in aerodynamic function of body and wing upstroke: Bird bodies generated relatively more lift than bat bodies, resulting in a more uniform spanwise lift distribution and higher span efficiency. A likely explanation would be that the bat ears and nose leaf, associated with echolocation, disturb the flow over the body. During the upstroke, the birds retract their wings to make them aerodynamically inactive, while the membranous bat wings generate thrust and negative lift. Despite the differences in performance, the wake morphology of both birds and bats resemble the optimal wake for their respective lift-to-drag ratio regimes. This suggests that evolution has optimized performance relative to the respective conditions of birds and bats, but that maximum performance is possibly limited by phylogenetic constraints. Although ecological differences between birds and bats are subjected to many conspiring variables, the different aerodynamic flight efficiency for the bird and bat species studied here may help explain why birds typically fly faster, migrate more frequently and migrate longer distances than bats

Conservation through management

The experience of naturalists indicate that many forest species have become more rare as a result of intensive forest management. As less dead wood is one of the key changes in most forests, saproxylic organisms tend to be especially vulnerable. So far, countermeasures have focused on setting aside reserves and key-habitats. However, while unmanaged reserves are likely to be important for many species, such areas provide little substrate for organisms adapted to habitats created by recent fires or other stand-level disturbances. Such species potentially benefit more from increased production and retention of dead wood in managed forest landscapes. This thesis evaluates artificially created high stumps as hosts for saproxylic beetles, and stumps and logs as substrates for saproxylic fungi. The studies are based on seven years of data from cut wood of various tree species, diameters and conditions of sun-exposure in Fagerön (Uppland, Sweden). The results demonstrate that hundreds of beetle species, including many red-listed species, utilise high stumps, and that two thirds of this fauna favours stumps in semi- or fully sun-exposed conditions. Thus, high stumps in logging areas and other open sites are potentially very valuable tools for conservation of saproxylic beetles. Cut wood, especially large diameter logs, also hosted numerous species of saproxylic fungi. Generally, most such species were little influenced by exposure. Thus, cut logs may support fungal diversity, both in managed forest landscapes and in forest reserves and key-habitats

Diverse ecological roles within fungal communities in decomposing logs of Picea abies

Fungal communities in Norway spruce (Picea abies) logs in two forests in Sweden were investigated by 454-sequence analyses and by examining the ecological roles of the detected taxa. We also investigated the relationship between fruit bodies and mycelia in wood and whether community assembly was affected by how the dead wood was formed. Fungal communities were highly variable in terms of phylogenetic composition and ecological roles: 1910 fungal operational taxonomic units (OTUs) were detected; 21% were identified to species level. In total, 58% of the OTUs were ascomycetes and 31% basidiomycetes. Of the 231 337 reads, 38% were ascomycetes and 60% basidiomycetes. Ecological roles were assigned to 35% of the OTUs, accounting for 62% of the reads. Wood-decaying fungi were the most common group; however, other saprotrophic, mycorrhizal, lichenized, parasitic and endophytic fungi were also common. Fungal communities in logs formed by stem breakage were different to those in logs originating from butt breakage or uprooting. DNA of specific species was detected in logs many years after the last recorded fungal fruiting. Combining taxonomic identification with knowledge of ecological roles may provide valuable insights into properties of fungal communities; however, precise ecological information about many fungal species is still lacking

The Use of Historical Collections to Estimate Population Trends - presentation at ECCB 2012

<p>Talk given at the 3rd European Congress of Conservation Biology in Glasgow (ECCB 2012), at the symposium "Applying citizen science generated species occurrence data in ecology and conservation research".</p> <p>Abstract:<br>For most species long term data to estimate population trends are lacking. Natural History Collections (NHCs) can provide such data for a wide array of taxa, but may suffer from biases due to e.g. varying sampling effort and changes in collector behaviour. In a case study utilizing Swedish longhorn beetles we analyzed population trends using data collected over 100 years, and focusing on a critical evaluation of sources of bias. Variability in sampling effort over time and space was controlled for using a species-specific estimate of effort, and we also took the increasing interest in threatened species during the 20th century into account. We found large intraspecific variation in population changes, from large declines to several hundred percent increases. However, most species showed stable or increasing ranges, and few seemed to decline in range. For some rare species, publication of new information on biology produced a drastic impact on the estimated abundance, and novel methods of detection sometimes affected species evaluations. Changes in collector´s preferences over time showed that estimated trends are likely to underestimate actual changes, both positive and negative. The results also suggested that species' declines may be overlooked if estimated only from changes in species range.</p